Question: Ishaan starts counting at 49, and he counts by fours. If 49 is the 1st number that Ishaan counts. what is the 9th number that he counts?
Solution: What is the first number that he counts? $49$ What is the second number that he counts? $\begin{align*}&49 + 4 \\ &= 53\end{align*}$ What is the third number that he counts? $\begin{align*}&49 + 4 + 4 \\ &= 49 + (2 \times 4) \\ &= 57\end{align*}$ What is the 9th number that he counts? $\begin{align*}&49 + (8\times4) \\ &= 49 + 32 \\ &= 81\end{align*}$